A synthetic route developed in our laboratory has made it possible to obtain several types of purine and pyrimidine carbocyclic nucleosides that were previously not attainable. Carbocyclic nucleosides are non-glycosidic nucleoside analogs in which the furanosyl sugar moieties have been replaced by hydroxylated cyclopentyl moieties. Several compounds from this unique series have demonstrated highly significant anti-viral and/or antitumor activities. These include carbocyclic ribofuranosyl, arabinofuranosyl, xylofuranosyl, lyxofuranosyl, aminoribofuranosyl, and deoxyribofuranosyl nucleosides. We plan to continue our efforts to produce new carbocyclic analogs based on recent developments. Our compounds will be divided into five categories: (1) Neplanocin analogs bearing the unique cyclopentene moiety, (2) 2'-modified 2',5'-oligoadenylate analogs to mimic interferon activity, (3) carbocyclic 5-azapyrimidine nucleosides, (4) carbocyclic aminonucleosides, and (5) carbocyclic nucleocidin analogs. All compounds will be tested for antitumor and antiviral properties. In vitro and limited in vivo antitumor testing will be performed in our laboratory using L1210 and P388 mouse leukemia cells. Active compounds will be prepared in larger quantities and sent to NCI. Antiviral testing will be continued by Dr. William M. Shannon, Southern Research Institute.